MONTPELIER — House lawmakers thumbed their noses at the federal courts Tuesday by passing a campaign-finance bill that would impose a $5,000 limit on donations to super PACs.

The Senate is less keen, however, on a provision that would no doubt trigger a costly constitutional challenge. And election watchdogs say the headline-grabbing super PAC language has diverted attention away from other provisions that would only heighten the influence of money on Vermont politics.

The House action comes less than a year after U.S. District Court Judge William Sessions issued a campaign-finance ruling in which he warned that Vermont likely has no legal authority to limit contributions to super PACs.

“The state has not offered a persuasive basis on which to limit contributions to a political action committee that only makes independent expenditures,” Sessions said in a 2012 case involving the Vermont Right to Life Committee.

Attorney General William Sorrell responded to Sessions’ decision by saying his office would no longer enforce the $2,000 contribution limit now written into statute. But House Speaker Shap Smith said last week he thinks the state can defend the $5,000 limit against constitutional challenge.

Sorrell said that if the Legislature passes the limit, he’ll do his best to defend it.

“There are arguments we can make — for example, trying to avoid corruption or the appearance of corruption of large monied interests in a political campaign,” Sorrell said.

But he said the case is anything but a slam dunk, and that a loss would put Vermont on the hook for the legal fees of whoever challenges the law. The state paid out $1.6 million in attorney fees when the U.S. Supreme Court tossed out Vermont’s previous attempts at limiting the money spent in elections.

Eve Jacobs-Carnahan, an assistant attorney general who specializes in campaign finance law, said costs to the state in another challenge could vary, depending on the type of case and how it’s litigated. But she said in an email that “if a party suing the state were to prevail in the lawsuit, it could cost the state several million dollars.”

That’s money that Sen. Jeannette White, chairwoman of the Senate Committee on Government Operations, said she isn’t willing to risk, especially on a provision she said has little hope of surviving a challenge.

And she said the last-minute changes by the House threaten passage of a bill that also contains heightened disclosure requirements aimed at helping Vermonters at least monitor who is funding super PACs and how the money is being spent.

Paul Burns, executive director of the Vermont Public Interest Research Group, said that as lawmakers try to tamp down on contributions to super PACs, they have actually increased limits on donations to statewide candidates, political parties and conventional political action committees.

Contribution limits to statewide candidates would jump from $2,000 to $4,000 per two-year cycle under the House plan; individual donations to parties and PACs would go from $2,000 to $5,000.

“There are many parts of this bill that actually increase the amount of money in politics, and we don’t really see the justification of that,” Burns said.

Members of the House and Senate will meet in the coming days to try to iron out a compromise in advance of what leaders say will be a Saturday adjournment.